I visited this site below on a homemade telescope and noted that the guy has seen the moon at 1,500 power:
http://www.geocities.com/telescope1999/14-5inch.html
I wonder if he can see the US flag on the moon set there by the Apollo astronauts over 30 years ago. Is it possible?
Only by landing on the moon and walking up to the flag. There are physical limits to what telescopes can see based on lens diameter. It is not possible to build a scope big enough to see small objects on the moon from the earth or for moon men to see the great wall of China.
Look at it this way; the moon is about a quarter of a million miles away. A 1500 power magnification makes it appear about 165 miles away. You’d be hard pressed to identify a city at that distance much less a flag.
So instead of seeming to be 240,000 miles away, the flag only seems to be 160 miles away? My guess would be no.
You can see the flag on the moon – just look at any of the old Apollo pictures
Not even the Hubble Space Telescope could resolve something as small as the flag on the moon. It is unlikely ANY such telescope will ever be built.
BTW welcome to SDMB JackL. You may want to read the posting guidelines as this post belongs in general questions. It’s a straightforward question with a factual answer.
There’s another factor. The moon is moving along at a pretty good clip. With an orbital radius of 240,000 miles and therefore an orbital distance of about 1.5 million miles, and an orbital period of about 28 days, the moon is zipping along at almost 54,000 miles/day, or 0.6 miles a second. Even if you could aim a powerful enough telescope, the image of a landing site would be a momentary blur across your lens. You could try to build a huge tracking telescope, but now you’re reaching the limits of what is possible even with modern (or feasible in the next few decades) engineering.
Alternately, you could put a small satelite in orbit around the moon and snap a bunch of pictures, but moon hoaxers have a fondness for the ridiculous and would probably claim the pictures were faked or the landing site materials were deposited by unmanned rockets. In any event, it’s a lot of trouble to go to in an attempt to convice some stubborn-for-the-sake-of-stubborn people.
Moderator’s Note: Since this is a question with a factual answer, I’ll move it over to our General Questions forum in case there are any remaining loose ends to tidy up.
All major telescopes already track to account for the rotation of the Earth. Why would it be such a big deal to account for the movement of the Moon?
I remember reading about a week ago that someone is going to photograph the landers, using an earth-based telescope.
Here’s the reference:
http://www.smh.com.au/articles/2002/11/24/1037697982142.html
They’re typically tracking stars, which are so far away that their apparant movement is much more gradual. Also, they’re not trying to photograph some tiny specific detail on the stars’ surfaces.
You can snap good-quality photographs of large lunar features like craters and whatnot and get minimal blurring, but when your targets get smaller and smaller, you’ll need faster exposures which means you’ll capture less light. Since the lunar Apollo objects aren’t generating light as the stars do (or reflecting sunlight to a large degree, as the moon’s albedo does) seeing them in any detail is going to pose a serious technical challenge. I’d be very impressed if the VLT can pick up more than a few vague dark spots representing the landers themselves. I’d be downright amazed if they could spot the flags in recognizable detail. In any event, I don’t expect it to rattle any devout hoax-believers.
I’m not sure if Hubble could see the flag, but I read the reason they hadn’t even tried was because the moon would be so bright it would damage the telescope, so they can never turn Hubble towards the moon.
Not true. Hubble has been aimed at the moon, but it can’t slew fast enough to track it. Instead, they aimed it at a point that the moon was going to cross and then made an image when they knew it was in the line of sight.
Distance matters not when it’s the angular movement of the earth that is being compensated for. Inexpensive scopes costing a few hundred dollars have that.
I agree with you, it shouldn’t be a problem on a modern telescope. It may be a problem on an equatorial mount which has an axis parallel to the earth’s axis and tracks stars by turning around this one axis at a fixed speed. But modern telescopes use alt-azimuth mounts with computerized control on both axes. With the proper software, such a telescope has no problem tracking a fast-moving comet or the Moon. Also the moon is extremely bright - it’s lit by full sunlight after all. Exposure time should be less than 1/10 second.
Tracking might be a problem on the Hubble though. Since space telescopes aren’t fixed to the ground, they use stars as reference points for pointing. The sensor on the Hubble is not designed to track a bright, complex pattern like the surface of the moon.
With ground based telescopes, the main problem is the earth’s atmosphere which blurs the images. Normally this limit is around 1 arcsecond, which means that the resolution of any telescope larger than 4 inch aperture is limited by atmosphere, not optics. I don’t know too much about the VLA but they must be using adaptive optics or interferometry if they hope to see the Apollo lander. Even then, I’d guess they are trying to see a shadow cast by the lander, not the lander itself.
The article states the scope can see a human hair at 16km, about ten miles. I find that extremely doubtful but even if so it’s a stretch to see small objects on the moon. Estimating ten one thousands of an inch for a human hair extrapolates to 20 feet as the smallest object the scope could resolve on the moon. That doesn’t mean detail on the object but the object appearing as a spec. An impressive feat but it won’t do much to debunk moon hoax believers.
Fine, but there’s a huge difference between photographing a star and trying to get details from the moon. You can leave your shutter open for about 30 seconds and get pinpoint images of stars (any shorter and the fainter stars won’t appear on film, any longer and they start to appear as streaks). In any case, a good photograph of a star shows just a point of light.
There is a huge difference between this and trying to snap a detailed image of an object on the Moon. If you cut your exposure down to even a hundredth of a second, the object will still move 0.006 miles, or 31.7 feet (using my earlier calculation of the Moon’s orbital speed). The landers, let alone the flags, are smaller than 31.7 feet. If you were photographing a stadium-sized object 1000 feet in diameter, the blur created by the 31.7’ movement wouldn’t be as significant. Let’s say you decided to go for 6400 speed film, so the apparant movement was only about 6 inches. You should be able to resolve the landing equipment, and possibly the flags (though they would still be blurred), but your exposure time is so short that you can’t capture enough light to get a recognizable image, unless your target was really really bright, and the landing equipment isn’t.
The VLT, with its huge effective lens, can capture immense amounts of light (well, immense by photography standards) which lets it snap very fast photos, though I’d still be amazed if they get anything more than a greyish smudge representing the larger artifacts. Even if they did, the hoaxers will claim that the objects were placed there by unmanned probes, or that the pictures have been faked or enhanced. Net effect: zip.
Note that reflectors were left on the moon during some of the landings and laser measurements from these are routinely done. They are used to accurately measure the distance to the moon over time. (Yet another thing that would have to be completely hoaxed involving too many people to keep secret, etc.)
Oh, and another thing. The Apollo capsules were photographed from Earth when they were in lunar orbit. They could only be spotted during the interval when they crossed the dark edge of the lunar terminator while still light from the Sun. Relatively small telescopes, such as those at the Portland State U. observatory in E. Oregon at the time, where able to do this.
Check out this photo taken by an earth-based telescope. It shows 130 meter resolution on the lunar surface!
http://spaceflightnow.com/news/n0208/12taruntius/
Sorry, but it looks like high lunar pics are possible!